A. Field of the Invention
The present invention relates to a method, apparatus, and system of aiming lighting fixtures, and in particular, to aiming lighting fixtures that have an optical system that produces a controlled, concentrated beam, for example, the type useful for sports lighting or large area lighting with a plurality of fixtures aimed at different directions to the target.
B. Problems in the Art
In lighting applications that use a plurality of controlled concentrated beams at different positions and angles relative to the target, it is possible to minimize the number of fixtures needed to accomplish the lighting task. As is well known in the art, by empirical methods or computer programs, a design can be created that calls for the number of fixtures, the beam widths and characteristics, and other parameters for given fixture locations. The plan includes aiming points for each fixture—where each fixture should be aimed to a specific point on the target area.
Sports lighting is an example of such an application. Arrays of multiple fixtures are elevated on poles at different locations around the field. Many times specifications direct the minimum light intensity and uniformity levels for the field, and above the field. If appropriately designed, the number of fixtures needed to adequately illuminate the field can be minimized. This can minimize cost of the system.
FIGS. 1A-F shows diagrams which exemplify these types of fixtures and lighting systems. As indicated in FIG. 1A, a plurality of poles A1, A2, B1, B2, each with a plurality of lighting fixtures 101, are spaced around field 100. Typically, fixtures 101 comprise a bowl-shaped reflector 102 with a glass lens 103 over its front open side. Its rear side is mounted to a bulb cone 104 which in turn is connected to an adjustable mounting knuckle 105. Mounting knuckle 105 is connected to cross arm 106. The adjustable mounting knuckle 105 allows for different aiming orientations of reflector 102.
FIGS. 2A-C illustrate a similar lighting system but for a different athletic field 100. Here there are 8 poles, identified as A1, A2, B1, B2, C1, C2, D1, and D2. Thirty-eight fixtures are distributed in arrays on each pole (see numbers 1, 2, 3, . . . and FIG. 2A). FIG. 2B is an example of what can be called an aiming diagram for each of those thirty-eight fixtures. It illustrates how a design or plan for the lighting system for that field 100 includes locations and heights of the eight poles and which pole each of the thirty-eight total fixtures will be mounted, as well as where each of fixtures 1-38 are to be aimed to different points on the field (see circled numbers 1-38 in FIG. 2B). FIG. 2B also indicates the type of beam produced from each fixture, the height above the ground, and other information pertinent to the design of the system. As is well known in the art, the aiming points (the circled numbers on field 100 in FIG. 2) are along a line between its corresponding fixture and a point on field 100. That line could be the optical axis of the fixture. Or, it could be what would be considered the center or most intense central point of the beam. In any event, the aiming point on the field is indicative of direction in free space that the fixture and its beam should be aimed and intersect with the field.
Line 170 in FIG. 2C illustrates diagrammatically the line between the fixture 101 and its aiming point on the field (basically in the center of the beam). Even though these beams are controlled and concentrated, they tend to disperse over distance. FIG. 2C shows diagrammatically the outer limits, in a vertical plane, of such a beam (see dashed lines indicating top 171 and bottom 172 of beam). It is to be understood that the center of the beam along axis 170 is most intense whereas the outer edges are much less intense.
The challenge in designing a lighting system with a minimum amount of fixtures is to meet uniformity and intensity minimums across the field. There cannot be any gaps in lighting or substantial unevenness of lighting. To accomplish this, the designs call for precise aiming of the fixtures to their designed locations. It is one thing to design the aiming locations. It is another thing to build and install it accurately. How well the design is implemented depends in large part on how close to the designed aiming points the fixtures actually end up when installed. Correct free space aiming of each fixture is not trivial. The fixtures can be fifty, one hundred, or more feet in the air, and poles can be tens of yards, or more, away from the aiming points. It is easy to find the designed aiming points on the field by using the field map or diagram generated from the design. One simply can measure and stake the physical locations of the aiming points on the two-dimensional field by reference to the map or diagram, such as FIG. 2B. But whether the fixtures are correctly aimed to those points cannot be reliably checked by just using the human eye.
Again, aiming diagrams such as FIG. 2B tell what optic systems are used for each fixture on each pole and the physical location of aiming points on the field for each fixture (e.g., where the center of the beam or optical axis of each fixture intersects with the field). The issue is how does one ensure, with accuracy, that the fixtures, once elevated on the pole, are aimed to their aiming locations.
It is not practical or even reasonably feasible to temporarily erect the fixtures, turn them on, and with the human eye see if the aiming axis intersects at the aiming point on the field. As is well known in the art, these beams are not pinpoint beams. They illuminate many square yards of the field. There is no precise center of the beam that could be identified within the needed accuracy. Furthermore, it would be difficult to even identify beam locations on a field in bright daylight. It would even be improbable that it could be done at nighttime. It would involve just a guess as to what the true beam aiming axis is by looking at a beam's projection on the field.
Therefore, a variety of methods have been attempted to deal with this issue.
Musco Corporation of Oskaloosa, Iowa has improved upon sports lighting aiming in the following ways. See, e.g., U.S. Pat. Nos. 5,398,478; 5,600,537; 6,340,790; and 6,398,392. These patents describe and illustrate systems that help the contractor install poles that are plumb and are incorporated by reference herein. A base 109 (FIG. 1D) has one end firmly in the ground in a plumb position and an upper end extending several feet above the ground. A tubular metal pole simply slip fits over the above-ground base. By careful manufacturing processes, if the pole is straight and the base is plumb, the top of the pole will be plumb. Furthermore, some of these patents have what is called a pole fitter (see reference number 107 in FIGS. 1D-G herein) that slip fits at the top of tubular metal pole section 108 (see FIGS. 1D-F and the incorporated-by-reference U.S. patents for further details). Musco Corporation markets these types of systems under the trademark LIGHT STRUCTURE™. The pole fitter has pre-attached cross arms 106 that are carefully manufactured. The pole fitter therefore would also be plumb and the cross arms be perpendicular to pole fitter 107 and pole 108. Therefore, when designing the lighting system, the precise position of each fixture 101 relative to field 100, and aiming points on field 100, is known because of the precise relationships of base 109, pole 108, pole fitter 107 and cross arms 106.
This still requires that the aiming axes of each fixture be correctly oriented to its corresponding aiming point on the field. Musco Corporation has developed a system of mounting knuckles 105 that allows the precise pan and tilt relationships of each fixture to its designed aiming point to be preset at the factory. The structure even allows shipment of pole fitter 107 with fixtures 101 attached but hanging straight down and then the installer just moves each fixture to an indicated orientation at the site of the field on the ground. Each fixture is then aimed according to the previously developed design (e.g., FIG. 2B) relative to its cross arm and pole fitter. The pole fitter is then mounted to pole 108 at ground level and then the combination of pole 108, pole fitter 107 (with its cross arms 106) and all of the pre-aimed fixtures 101 is lifted and set down on top of base 109. The advantage is that final aiming of all the fixtures on a single pole should then require only that the pole be rotated (if needed) to a position where the aiming axes 110 of the fixtures should go to the designed aiming locations on the field.
While this has greatly simplified and made more efficient the erection of these types of lighting systems, the final step still is troublesome. How does one ensure that at least one of the fixtures aiming axis 110 (FIG. 3) is accurately aimed to its aiming point?
One way that has been tried is to have a worker stand at an aiming point on the field relative to a pole and, with binoculars, look into the interior of the fixture. If it appears that some structure inside the fixture is in appropriate alignment with the line of sight of the worker through the binoculars, it is assumed that fixture is correctly aimed and thus all fixtures on that pole correctly aimed. However, it has been found to be difficult to get very accurate. Even experienced workers may not get closer than within 5-10 feet of accuracy. Furthermore, some fixtures are harder than others to practice this method. Some glass lenses do not allow a clear view into the interior. There could be reflections or lighting conditions that make it difficult. It has to happen without the fixture's light source on for a view to be made of parts inside the fixture.
Another method places some indicia (e.g., a colored ring of several inches diameter) on the lens of the fixture in direct concentric alignment with the aiming axis of the fixture. The worker stands at the aiming location with binoculars and checks if that circle lines up concentrically with structure in the fixture, such as the end of the bulb or the back of the reflector at its apex. This has the same issues as the previously discussed method. Although it may sometimes be easier to see the ring on the lens, it has proven to be difficult to get needed accuracy on determining, within needed accuracy, whether the fixture is correctly aimed.
Another issue exists. Current methods tend to require one person on the field checking for aiming angles of fixtures and at least one worker at the pole with machinery capable of rotating the pole or adjusting individual fixtures or crossarms in response to instructions of the worker on the field. There is a need in the art for improvement in the amount of time and labor needed to get final aiming of the fixtures and arrays of fixtures.